Adopt `bazel_platforms` as the single source of truth for build platforms

[dcalavrezo-qorix]

Description

We need to standardize how build platforms are defined across the S-CORE ecosystem by using the eclipse-score/bazel_platforms repository as the single source of truth.

Background

The bazel_platforms repository serves as the central definition hub for S-CORE Bazel platforms and constraints.
It is designed to:

• Provide global constraints that complement Bazel’s standard set, enabling more precise environment description and selection.
• Define consistent platform configurations to ensure seamless and uniform toolchain selection across all S-CORE modules.
• Promote compatibility, reproducibility, and clarity in build environment definitions.

Required actions

1. Identify all repositories currently defining local platforms (e.g., in toolchains_qnx, toolchains_rust, module_template, etc.).
2. Decouple those platform definitions from the toolchain repositories.
3. Reference the centralized bazel_platforms repository instead, using appropriate Bazel module dependencies or workspace overrides.
4. Update documentation and CI configurations to reflect the new platform source.

[jgetas]

I'd like to raise this topic again because we miserably fail to even understand how cross-building is supposed to work with bazel. IMHO it's beneficial to start with requirements and then try to break them down to how to implement them with bazel, toolchains and platforms.

If such requirements already exist, please let me know. What I have in my mind is requirements like these:

SCORE build system requirements proposal

"target" is used for a emulation environment or hardware board with determined CPU architecture.
"SCORE distribution" is referred in the sense of the collection of binary components built for a single target.
"toolchain" is referred as the collection of tools required to build all required components for a target. This comprises of especially all language compilers (C/C++, Rust, ...)

1. The SCORE distribution shall be built for following targets:
   a. QNX 8.0 aarch64 QEMU
   b. QNX 8.0 x86_64 QEMU
   c. Raspberry PI4 Linux Debian Trixie (?)
   d. Ubuntu 24.04 Linux x86_64

2. The SCORE distribution build system shall support building with a custom build toolchain. For example

   • using a custom QNX QOS SDP provided by customer.
   • using a custom cross Linux Yocto SDK.

3. The SCORE distribution build system shall ensure that its components and dependent components are built with the same toolchain.
   This is to establish compatibility between the components and with the target software environment.

[AlexanderLanin]

@odra @opajonk could you point to the issues, discussions, docu where this was discussed?

[opajonk]

This has proven to be a complex topic, of which the target and toolchain selection is just the "technical manifestation" ;-) I think the best entry-point to the "organizational topic" is this issue: eclipse-score/score#1740. Using bazel_platforms consistently everywhere is just one small aspect of this. But yes, it should be done - for sure.

[dcalavrezo-qorix]

Hi @dcalavrezo-qorix,

Is this issue still relevant? If not, please add the trash label so it can be marked for deletion.

[dcalavrezo-qorix]

@AlexanderLanin not sure if bazel_platfroms is used as the single source of truth for all modules. That has to be groomed and afterwards we can close the ticket.